[ldolse]

Originally Posted by kovidgoyal

Looking at the mechanize source code, all you have to do is construct a Request object and manually add the content-type header to it. If the request object has the content-type header it will not be overridden

By construct a request object, you mean something roughly equivalent to this? (from gui2.update.py):

                br = browser()
                req = mechanize.Request(URL)
                req.add_header('CALIBRE_VERSION', __version__)
                req.add_header('CALIBRE_OS',
                        'win' if iswindows else 'osx' if isosx else 'oth')
                req.add_header('CALIBRE_INSTALL_UUID', prefs['installation_uuid'])
                version = br.open(req).read().strip()